1. Field of the Invention
The present invention relates to an intraocular lens which comprises a lens body having an optical portion, and a support member extending radially outwardly from the lens body for holding the lens body in position within the eye. The invention is also concerned with a method of producing such an intraocular lens.
2. Discussion of the Related Art
There has been known an intraocular lens which comprises a generally circular lens body including an optical portion, and at least one support member in the form of an elongate thin filament, which is inserted at its one end into and fixed within a mounting hole that is open in the circumferential surface of the lens body. The support member needs to be firmly fixed to the lens body, to hold the lens body in position within the eye with high stability.
JP-A-5-56988 discloses a method of fixing the support member to the lens body, wherein an adhesive (prepolymer) is used to chemically bond the support member to the lens body by polymerization of the adhesive. JP-B-6-24543 discloses a method of fixing the support member to the lens body, wherein the support member has an anchoring portion in the form of a bulb or a loop formed at its proximal end at which the support member is fixed to the lens body. The anchoring portion of the support member is embedded in the lens body, to thereby fix or anchor the support member to the lens body. JP-A-7-503148 discloses a method of fixing the support member to the lens body, by inserting the proximal end portion of the support member in a fixing hole formed in the lens body, and laser-welding the support member, so that the support member is fixed to the lens body.
The method disclosed in JP-A-5-56988 suffers from a problem of a residual monomer after the support member has been bonded to the lens body, which residual monomer would arise from the use of the prepolymer as an adhesive. Accordingly, this method gives rise to a problem of insufficient safety. In addition, it is difficult to prepare the adhesive, and determine the amount of the adhesive to be used. In the method of JP-B-6-24543, it is difficult to form the anchoring portion having a predetermined shape at the proximal end portion of the support member, making the fabrication of the intraocular lens cumbersome. In the method of JP-A-7-503148, there is a risk that the material, shape, and mechanical strength of the lens body which includes the optical portion may be adversely influenced by the laser beam used in welding the support member, for fixation thereof to the lens body. Accordingly, none of those disclosed methods are satisfactory, and there has been a need for an improved method of fixing the support member to the lens body.